In "Ericsson review" No. 1, 1980 there is generally described an automatic public mobile telephone system for connecting motorized subscribers to each other via the public telephone network. The basic units included in such a system, such as mobile subscriber equipment (mobile stations), base radio stations and telephone exchange equipment are described in the article. In particular there is described the so-called "hand-off" function (see page 30 "switch-pver principles"), i.e. when a mobile subscriber is switched over during a call in progress from one base station to another in the case where the mobile subscriber moves from the coverage area of one base station to the coverage area of the adjacent base station.